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Message-ID: <d3ade685-871c-8ae9-ec57-c3446001cf59@kernel.org>
Date:   Fri, 4 Feb 2022 20:03:13 +0800
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Subject: Re: [f2fs-dev] [PATCH v2] f2fs: add a way to limit roll forward
 recovery time
Content-Language: en-US
To:     Jaegeuk Kim <jaegeuk@kernel.org>
Cc:     linux-kernel@vger.kernel.org,
        linux-f2fs-devel@lists.sourceforge.net
References: <20220127214102.2040254-1-jaegeuk@kernel.org>
 <YfsjEb2ii3eyPzng@google.com>
 <142d2cc9-73f2-f9fa-2543-6426c62e77a6@kernel.org>
 <YfwT/6bSqUqUF/B3@google.com>
 <211c28eb-789e-e6e6-5daf-8040ac5ddd93@kernel.org>
 <YfzEuA6XdnJ6nibk@google.com>
From:   Chao Yu <chao@kernel.org>
In-Reply-To: <YfzEuA6XdnJ6nibk@google.com>
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On 2022/2/4 14:16, Jaegeuk Kim wrote:
> On 02/04, Chao Yu wrote:
>> On 2022/2/4 1:42, Jaegeuk Kim wrote:
>>> On 02/03, Chao Yu wrote:
>>>> On 2022/2/3 8:34, Jaegeuk Kim wrote:
>>>>> This adds a sysfs entry to call checkpoint during fsync() in order to avoid
>>>>> long elapsed time to run roll-forward recovery when booting the device.
>>>>> Default value doesn't enforce the limitation which is same as before.
>>>>>
>>>>> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
>>>>> ---
>>>>> v2 from v1:
>>>>>     - make the default w/o enforcement
>>>>>
>>>>>     Documentation/ABI/testing/sysfs-fs-f2fs | 6 ++++++
>>>>>     fs/f2fs/checkpoint.c                    | 1 +
>>>>>     fs/f2fs/f2fs.h                          | 3 +++
>>>>>     fs/f2fs/node.c                          | 2 ++
>>>>>     fs/f2fs/node.h                          | 3 +++
>>>>>     fs/f2fs/recovery.c                      | 4 ++++
>>>>>     fs/f2fs/sysfs.c                         | 2 ++
>>>>>     7 files changed, 21 insertions(+)
>>>>>
>>>>> diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs
>>>>> index 87d3884c90ea..ce8103f522cb 100644
>>>>> --- a/Documentation/ABI/testing/sysfs-fs-f2fs
>>>>> +++ b/Documentation/ABI/testing/sysfs-fs-f2fs
>>>>> @@ -567,3 +567,9 @@ Contact:	"Daeho Jeong" <daehojeong@google.com>
>>>>>     Description:	You can set the trial count limit for GC urgent high mode with this value.
>>>>>     		If GC thread gets to the limit, the mode will turn back to GC normal mode.
>>>>>     		By default, the value is zero, which means there is no limit like before.
>>>>> +
>>>>> +What:		/sys/fs/f2fs/<disk>/max_roll_forward_node_blocks
>>>>> +Date:		January 2022
>>>>> +Contact:	"Jaegeuk Kim" <jaegeuk@kernel.org>
>>>>> +Description:	Controls max # of node block writes to be used for roll forward
>>>>> +		recovery. This can limit the roll forward recovery time.
>>>>> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
>>>>> index deeda95688f0..57a2d9164bee 100644
>>>>> --- a/fs/f2fs/checkpoint.c
>>>>> +++ b/fs/f2fs/checkpoint.c
>>>>> @@ -1543,6 +1543,7 @@ static int do_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
>>>>>     	/* update user_block_counts */
>>>>>     	sbi->last_valid_block_count = sbi->total_valid_block_count;
>>>>>     	percpu_counter_set(&sbi->alloc_valid_block_count, 0);
>>>>> +	percpu_counter_set(&sbi->rf_node_block_count, 0);

Should be initialized before use?

Thanks,

>>>>>     	/* Here, we have one bio having CP pack except cp pack 2 page */
>>>>>     	f2fs_sync_meta_pages(sbi, META, LONG_MAX, FS_CP_META_IO);
>>>>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>>>>> index 63c90416364b..6ddb98ff0b7c 100644
>>>>> --- a/fs/f2fs/f2fs.h
>>>>> +++ b/fs/f2fs/f2fs.h
>>>>> @@ -913,6 +913,7 @@ struct f2fs_nm_info {
>>>>>     	nid_t max_nid;			/* maximum possible node ids */
>>>>>     	nid_t available_nids;		/* # of available node ids */
>>>>>     	nid_t next_scan_nid;		/* the next nid to be scanned */
>>>>> +	nid_t max_rf_node_blocks;	/* max # of nodes for recovery */
>>>>>     	unsigned int ram_thresh;	/* control the memory footprint */
>>>>>     	unsigned int ra_nid_pages;	/* # of nid pages to be readaheaded */
>>>>>     	unsigned int dirty_nats_ratio;	/* control dirty nats ratio threshold */
>>>>> @@ -1684,6 +1685,8 @@ struct f2fs_sb_info {
>>>>>     	atomic_t nr_pages[NR_COUNT_TYPE];
>>>>>     	/* # of allocated blocks */
>>>>>     	struct percpu_counter alloc_valid_block_count;
>>>>> +	/* # of node block writes as roll forward recovery */
>>>>> +	struct percpu_counter rf_node_block_count;
>>>>>     	/* writeback control */
>>>>>     	atomic_t wb_sync_req[META];	/* count # of WB_SYNC threads */
>>>>> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
>>>>> index 93512f8859d5..0d9883457579 100644
>>>>> --- a/fs/f2fs/node.c
>>>>> +++ b/fs/f2fs/node.c
>>>>> @@ -1782,6 +1782,7 @@ int f2fs_fsync_node_pages(struct f2fs_sb_info *sbi, struct inode *inode,
>>>>>     			if (!atomic || page == last_page) {
>>>>>     				set_fsync_mark(page, 1);
>>>>> +				percpu_counter_inc(&sbi->rf_node_block_count);
>>>>
>>>> if (NM_I(sbi)->max_rf_node_blocks)
>>>> 	percpu_counter_inc(&sbi->rf_node_block_count);
>>>
>>> I think we can just count this and adjust right away once sysfs is changed.
>>
>> Since this long recovery latency issue is a corner case, I guess we can avoid this
>> to save cpu time...
> 
> I think we can show this in debugfs, as it won't give huge overhead.
> 
>>
>> BTW, shouldn't we account all warn dnode blocks? as we will traverse all blocks there
>> in warn node list.
> 
> I thought we don't need to track the whole bunch of chains, but would be enough
> to record # of fsync calls roughly.
> 
>>
>> Thanks,
>>
>>>
>>>>
>>>> Thanks,
>>>>
>>>>>     				if (IS_INODE(page)) {
>>>>>     					if (is_inode_flag_set(inode,
>>>>>     								FI_DIRTY_INODE))
>>>>> @@ -3218,6 +3219,7 @@ static int init_node_manager(struct f2fs_sb_info *sbi)
>>>>>     	nm_i->ram_thresh = DEF_RAM_THRESHOLD;
>>>>>     	nm_i->ra_nid_pages = DEF_RA_NID_PAGES;
>>>>>     	nm_i->dirty_nats_ratio = DEF_DIRTY_NAT_RATIO_THRESHOLD;
>>>>> +	nm_i->max_rf_node_blocks = DEF_RF_NODE_BLOCKS;
>>>>>     	INIT_RADIX_TREE(&nm_i->free_nid_root, GFP_ATOMIC);
>>>>>     	INIT_LIST_HEAD(&nm_i->free_nid_list);
>>>>> diff --git a/fs/f2fs/node.h b/fs/f2fs/node.h
>>>>> index 18b98cf0465b..4c1d34bfea78 100644
>>>>> --- a/fs/f2fs/node.h
>>>>> +++ b/fs/f2fs/node.h
>>>>> @@ -31,6 +31,9 @@
>>>>>     /* control total # of nats */
>>>>>     #define DEF_NAT_CACHE_THRESHOLD			100000
>>>>> +/* control total # of node writes used for roll-fowrad recovery */
>>>>> +#define DEF_RF_NODE_BLOCKS			0
>>>>> +
>>>>>     /* vector size for gang look-up from nat cache that consists of radix tree */
>>>>>     #define NATVEC_SIZE	64
>>>>>     #define SETVEC_SIZE	32
>>>>> diff --git a/fs/f2fs/recovery.c b/fs/f2fs/recovery.c
>>>>> index 10d152cfa58d..1c8041fd854e 100644
>>>>> --- a/fs/f2fs/recovery.c
>>>>> +++ b/fs/f2fs/recovery.c
>>>>> @@ -53,9 +53,13 @@ extern struct kmem_cache *f2fs_cf_name_slab;
>>>>>     bool f2fs_space_for_roll_forward(struct f2fs_sb_info *sbi)
>>>>>     {
>>>>>     	s64 nalloc = percpu_counter_sum_positive(&sbi->alloc_valid_block_count);
>>>>> +	u32 rf_node = percpu_counter_sum_positive(&sbi->rf_node_block_count);
>>>>>     	if (sbi->last_valid_block_count + nalloc > sbi->user_block_count)
>>>>>     		return false;
>>>>> +	if (NM_I(sbi)->max_rf_node_blocks &&
>>>>> +			rf_node >= NM_I(sbi)->max_rf_node_blocks)
>>>>> +		return false;
>>>>>     	return true;
>>>>>     }
>>>>> diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
>>>>> index 281bc0133ee6..47efcf233afd 100644
>>>>> --- a/fs/f2fs/sysfs.c
>>>>> +++ b/fs/f2fs/sysfs.c
>>>>> @@ -732,6 +732,7 @@ F2FS_RW_ATTR(SM_INFO, f2fs_sm_info, min_ssr_sections, min_ssr_sections);
>>>>>     F2FS_RW_ATTR(NM_INFO, f2fs_nm_info, ram_thresh, ram_thresh);
>>>>>     F2FS_RW_ATTR(NM_INFO, f2fs_nm_info, ra_nid_pages, ra_nid_pages);
>>>>>     F2FS_RW_ATTR(NM_INFO, f2fs_nm_info, dirty_nats_ratio, dirty_nats_ratio);
>>>>> +F2FS_RW_ATTR(NM_INFO, f2fs_nm_info, max_roll_forward_node_blocks, max_rf_node_blocks);
>>>>>     F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, max_victim_search, max_victim_search);
>>>>>     F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, migration_granularity, migration_granularity);
>>>>>     F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, dir_level, dir_level);
>>>>> @@ -855,6 +856,7 @@ static struct attribute *f2fs_attrs[] = {
>>>>>     	ATTR_LIST(ram_thresh),
>>>>>     	ATTR_LIST(ra_nid_pages),
>>>>>     	ATTR_LIST(dirty_nats_ratio),
>>>>> +	ATTR_LIST(max_roll_forward_node_blocks),
>>>>>     	ATTR_LIST(cp_interval),
>>>>>     	ATTR_LIST(idle_interval),
>>>>>     	ATTR_LIST(discard_idle_interval),